This invention relates to surgical instruments and more specifically concerns the sterilization of surgical implantables in vivo by electrical means.
Any time an incision is made in the body there is the possibility of infection due to pathogenic microorganisms entering through the incision. If an appliance or a device is implanted there is also the possibility of such microorganisms being present on the appliance or device.
It is known that the healing of various skin lesions and ulcers may be accelerated by electrotherapy techniques involving the application of low intensity direct current through electrodes attached to the area adjacent to the pathologic tissue. In a copending U.S. application, Ser. No. 545,609, filed Jan. 30, 1975 by your applicants, it is disclosed that the use of silver or silver bearing material in the construction of the positive electrode further aids the healing process by providing a bactericidal effect. One explanation of this effect is that positive silver ions are formed which chemically bind with the DNA molecules of the bacteria and prevent reproduction thereof.
Apparatus disclosed in Ser. No. 545,609 provides current to promote tissue growth, while bactericidal action is a desirable secondary effect.
Many surgical and dental devices are normally electrically passive. It is desirable during use to provide bactericidal action on the device and in the tissue about the implantation site of the device. In U.S. Pat. No. 2,121,875 by W. Kruse et al., there is taught a process for sterilizing and disinfecting water, surgical instruments, root canals of teeth and catheters. A silver bearing electrode is used as an anode in a direct current path. Kruse calls for pretreating the anode so that it is coated with silver compounds before use. A high current density is also called for, the total current being in the milliampere range for treating the electrode during sterilization of a root canal.
In contrast, the present invention calls for low current to be continuously applied to an electrode so as to liberate silver ions from the electrode.